1. Used as an interjection to affirm something, usually enthusiastically. A: "Do you really think we have a chance at winning?" B: "Oh yeah! I think we have a great chance!"

2. Used as interjection to express interest in something someone is saying. A: "My father works as a piano tuner." B: "Oh yeah? How'd he get into that?"

3. Used as an interjection to express disbelief of or childish hostility toward something someone is saying. A: "One of these days, I'll be running this place." B: "Oh yeah? Let me know how that turns out for you." A: "You're just a big stupid head!" B: "Oh yeah? Well, you're a bigger, stupider head!"

4. Used as interjection to indicate that one has just remembered or thought of something. Oh yeah, that's what I wanted to ask you: where did you get that suit? A: "And then you just restart the computer to finish installing the software." B: "Oh yeah, duh, I knew that."